Posted
by
Zonkon Saturday December 30, 2006 @04:41AM
from the that-explains-hollywood-zing dept.

odie_q writes "It has long been known that the Toxoplasma gondii parasite alters its host's behavior, but now it seems the way it alters it depends on the sex of the host. From the article: 'A common parasite can increase a women's attractiveness to the opposite sex but also make men more stupid, an Australian researcher says ... Infected men have lower IQs, achieve a lower level of education and have shorter attention spans. They are also more likely to break rules and take risks, be more independent, more anti-social, suspicious, jealous and morose, and are deemed less attractive to women. On the other hand, infected women tend to be more outgoing, friendly, more promiscuous, and are considered more attractive to men compared with non-infected controls.'"

For those who didn't RTFA, one of the ways of catching this disease is by accidentally digesting cat feces (if the cat is effected with the bacteria). Smokey is a fairly common name for a grey cat here in the States.

What are the odds that guys with low IQs, short attention spans, and an affinity for risks are just more likely to eat undercooked meat, and that the more outgoing promiscuous women catch it because of them.

Unfortunately it's true. What happens is, cats can carry the parasite on their fur from contact with feces, then brush up or rub against something you touch. Example, cat wipes its parasites off on your couch. You sit down unaware it did that. Your hand touches the couch, picks up some very small toxoplasmosis eggs; you sit there watching TV, eating popcorn, not having washed your hands. You've been pwned by the parasite. Worse, very worse, is that small children can get it by touching the cute kitty then

How do you like your steak? Unless your answer is "well done", you are at greater risk for toxoplasmosis than any cat owner.

From wikipedia: "The most common means of transmission to humans is raw or undercooked meat."

Further, based on research it is *extremely* unlikely that you could pick up this parasite from casual contact with cats. Handling cat feces and not washing your hands? Sure. Petting a cat? No way.

From wikipedia: "Although the pathogen has been detected on the fur of cats, it has not been found in an infectious form, and direct infection from handling cats is generally believed to be very rare."

Further, cats must contract the disease from somewhere and are only infectious for a brief period right after contracting the disease. Which means that indoor cats that don't have access to infected prey can't get the disease (except by other transmission methods which are the same for humans). Or, if your cat already has toxoplasmosis, it means that it can't transmit the parasite to you (except for that brief period right after infection.

From wikipedia: "Cats excrete the pathogen in their faeces for a number of weeks after contracting the disease, generally by eating an infected rodent. Even then, cat faeces are not generally contagious for the first day or two after excretion, after which the cyst 'ripens' and becomes potentially pathogenic. Studies have shown that only about 2% of cats are shedding at any one time, and that shedding does not recur even after repeated exposure to the parasite."

Further, the disease *is* treatable. The cysts are resistant to common forms of treatment for parasites (antibiotics). However, there are treatments available which seem to eliminate the cysts.

From wikipedia: "The antibiotic atovaquone has been used to kill Toxoplasma cysts in situ in AIDS patients.[3] In mice, a combination of atovaquone with clindamycin seemed to optimally kill cysts."

Every time a toxoplasmosis article comes up, someone will make a post like this, saying that *for them* cat ownership is simply too risky. This, of course, completely ignores the reality of the situation, where cat ownership is actually far less risky than eating, where mishandling of food or "undercooked" meat (may I be the first to say, yum!) are far more likely to score you an infectious parasite.

It is invalid logic to reason that the risk is greater from eating raw steak than from handling a cat, so that handling cats is not of concern. Both are of concern.

Whaaa? Based on research, undercooked meat is the most common transmission vector for the disease. This isn't a guess, it's a fact. Also a fact: unless you handle cat feces, you have almost no chance of getting the disease from a cat. Let me quote this again: "Although the pathogen has been detected on the fur of cats, it has not been found

My point was your claim was that undercooked meat was far more important, so ignore cats. That viewpoint is illogical. A threat is still a threat even if a more common threat exists. "It all comes down to probability." Please do not apply financial industry reasoning about monetary risk to medical situations, that's not entirely valid.

Seriously. He used to be quite articulate. I just saw a youtube snippet of him talking fast, articulate, and using big words in the mid 90's. It was like a different man. Something changed him into a stubburn bumbler. Some speculate drug abuse, but everyone around him says he swore off substance abuse decades ago.

"Never attribute to malice what can be explained by incompetence".I so hoped that George W. Bush would win the 2004 elections to make sure he is still president when the failure of his presidency becomes more clear. So no one can blame the ongoing breakdown in Iraq and the reappearing Taliban in Afghanistan to a liberal and weak Democrat administration which messes anything up the Bush Administration has started.

I was starting to wonder if the strategies of the Bush administration might just be based on com

As I've said here before, the similarities between Brazil's president Lula and George Bush are astoundingly big.Both of them find out that there's a huge proportion of their electorates that are people who don't like to read, and are resentful of intelectuals. Both of them realized that this people constitute the majority of the people of their countries. And both of them discovered that the best way to capitalize those votes was to *act* just like that people. So, whenever they are in public or TV they *in

It's been suggested that his famous train-wreck ability with language is due to the effort of deliberately being something other than what he started as. Kind of like how (allegedly) left-handers who are forced to become righties tend to stutter at the early stages. The down-homisms just aren't natural, and the fundamentalist streak means that he doesn't understand why he has to explain anything. Being forced to do both creates the bushisms.

I found this piece of news very interesting. Is it known how the parasite affects our behavior? If it secretes a chemical that has the effect, I'd say this could be used for treatment in a variety of medical conditions. If it "attacks" specific areas of the brain, it may reveal interesting things about it.

Things such as this hints to how our minds work, which is possibly one of the most fascinating things in the universe (:

"The virus broke down barriers between clearly separated brain parts and made them more equal in reasoning on how to behave"

The barriers are required for consciousness as your first link clearly describes. If you want to see what the world looks like without the barriers then injest some psilocybe. You won't actually be doing any reasoning though. The next true phase of mind evolution will be the combination of computers with the brain, as to how that will happen, I don't know.

I did. The causal relationship was demonstrated, but on lab rats. As far as humans are concerned, all that was done (as usual) was to find a correlation between having the parasites in your system and having certain personality traits. Things like "Does their personality change if you remove the parasites?" test was performed on the rats, but not on humans, rather it was assumed that "causal relationship with rats" == "causal relationship with humans."

The researchers have noted that toxoplasmosis secretes domanine-like molecules in mice. It has already been established that mice and humans share receptors for this molecule. It has already been established that dopamine levels affect human behaviour and mood. Mutatis mutandis, toxoplasmosis affects human behaviour and mood.

Actually, I don't see why that particular effort would help. Obviously, being a cat owner would be a risk factor (assuming you were exposed to the cat's feces during the period when it is infectious, which is a few weeks after the cat is infected, so I gather). But so is gardening or exposure to rodents and other small animals. A better comparison would be of people who are infected with toxoplasma yet who aren't cat-owners. Being a cat owner involves a complex situation (eg, economic factors like living in

Actually, if you want to bring up Occam's Razor, what about the explanation that the parasite merely makes both sexes stupider, and the higher attractiveness in women is because men like stupid (ditzy) women.

The article clearly states that the changed behaviour could be seen after infecting the mice with toxoplasmose and be reversed by treating the infection. So we have something that looks a lot more like a causation and less a pure correlation (with currently unknown relation).

I believe this is one of those news stories that sits around waiting for a slow news day. The original paper was released in November. It's written by Kevin Lafferty [usgs.gov] and was published in Proc. Roy. Soc. B [royalsoc.ac.uk].

It's a really quite fascinating paper - I recommend tracking it down if you can get access. Here's how it goes: Toxoplasmia gondii is adapated to live in cats and reproduces in felid intestinal cells & is shed, encysted, in their feaces. Then it can directly infect cats who come into contact with the cysts, or it encysts in brains of smaller mammals, and moves up the food chain as they get eaten until it hits a cat, and can reproduce again.

Fascinatingly, T.g. appears to affect rodent behavior to increase predation risk - i.e. the rodents become more active, less fearful of cat/cat smells, and have increased dopamine levels (which supposedly leads to novelty seeking behavior and neuroticism-type behaviors, or at least, they do in humans).

Despite humans not having any major cat predators, it could still affect us as a byproduct type of thing. Particularly that whole dopamine increase - this is should increase neuroticism levels.

Unfortunately I think the populations he uses for his stats are a little bit suspect (always the problem with worldwide analyses though), but it's definitely worth a read. You should also keep in mind that so far it's only an interesting correlation and not a direct demonstration that T.g. causes large scale cultural differences.

this is a field study, not an experiment!!!!!!!!!!!!!!!!!38% of the variance in the observered behaviour (answers in the fpi) is explained by the predictor variable.an r2 of 0.95 would mean, that the maximum correlation of another predictor could be 0.22 and you would have explained all human behaviour regarding the setting. think of zombie movies.

that said, i am not a big fan of the neo-fpi. it is a questionaire which means it reports how people see themself or want other to see them. plus, it is based on

You have been infected with a rare and deadly disease. A new drug has become available. In clinical trials, if people are left untreated (control group), only 31% survive and the rest die. If they are given the drug, 69% survive. Do you take the drug, or ignore it because its effects are "unimpressive"? Because that example expresses an effect size of r=0.38 [nih.gov].

The "anywhere else" you refer to is in areas of science that deal with deterministic phenomena. In many areas of social science, medicine, and other fields, the phenomena are probabilistic, and effect sizes are judged accordingly.

As if we didn't have enough biological disadvantages in the mating game, this one is nature's way of applying the final curb stomp.

Yes, the parasite secretes a green substance which makes one butt cheek look unusually padded. It's called Richitosis, and you get it by having lots of money. Symptoms include driving a sports car and living in a mansion.

I am pretty sure this is a dupe and was already discussed to death. I am trying to fight the slashdot search engine but up to now "parasite" and "toxoplasm" did not give any search result back... Maybe someone can point out what article it was ?

...infected women tend to be more outgoing, friendly, more promiscuous, and are considered more attractive to men

Perhaps it's just me, but my first thought after reading the summary was that the best and brightest the world of cosmetics marketing has to offer are probably working on the advertising campaign right now. "New, from L'Oreal: toxoplasmosis, the only parasite derived from cat shit that's/guaranteed/ to make you MORE ATTRACTIVE to the opposite sex. Because you're worth it!"...

Given the crap they already get women to shell out fifty quid for a couple of ounces, parasite-infected cat shit would be a relatively easy sell.

It doesn't look to me as this is a terminal illness, the infection is gone in a few weeks to months, so it's hardly an explanation for the world's stupidity.

It can be lethal if you have a weakened immune system due to age, chemo, HIV, whatever. BTW- it may persist as a low-grade infestation even in healthy people. The same as many other infections like syphilis, Lyme Disease, and even chickenpox - the initial symptoms of infection may go away but the pathogen stays in the body and causes mayhem a few years or even decades later.

It sounds like the parasite simply amplifies the affects of certain sex hormones in both sexes, and lowers inhibitions... In civilized men, too much of a good thing. (For less civilized men, it means "Jackass: The movie".) As for women, it's hard to draw conclusions about the intelligence of someone who's "more outgoing, friendly, more promiscuous". Some would consider that to be potentially more "risky," regardless of the fact that most m

If the parasite works by increasing dopamine levels in the brain, that would most certainly not decrease attention span or reaction time, it would in fact improve them, as can be seen when you take any dopaminergic drug. Higher dopamine doesn't hinder academic achievement, nor will it lower your IQ. That is ridiculous-- most of the mental benefits from cardiovascular exercise come from increased DA levels. Further, the effects of dopamine are not so sexually dimorphic in humans, the only real difference is that estrogen increases DA sensitivity. The archetypal drugs for increasing DA levels? Ritalin and Adderall.

These are low quality studies and an abomination of science to conclude that correlation = causation. Nothing is further from the truth! The main way toxoplasma is spread in humans is in eating undercooked meat. Considering the actual effects of dopamine on the brain, doesn't it seem more likely that perhaps a low IQ, low educational achievement, and risk taking/promiscuous behavior predispose one to eat or undercook meat? But even that is untested.

In the year 2007, a parasite is released into the earth's atmosphere rendering women more aggressive and men more dumb. The balance of power shifts and men become subservient to women. And when things can't seem to get any worse, the true intent of the parasite surfaces. (cue in action music)

I remember reading a few months ago that some reseachers had a found a higher incidence of schizophrenia among persons who, when small children, had had cats in their households, leading some to believe that Toxoplasmosis gondii may be a causal factor. Apparently, it is claimed that new research has confirmed this [schizophrenia.com]. This is of personal interest to me because my 14 year-old son was infected by Toxoplasmosis a couple years ago during a vist to Trinidad. Physicians suspect that the most likely source was my wife's aunt's home-made yogurt, which my kids love. My wife's aunt is an animal lover, and keeps numerous dogs and cats, as well as feeding hosts of wild birds that descend on the house every morning.

It was discovered after he complained about spots in his vision, and an opthalmological determined that there was a lesion on his retina which was flaking away. A blood test confirmed the presence of Toxoplasmosis gondii. Now he has to have an annual examination to ensure that the parasite is being kept under control by antibiotics, but it's always an extremely apprehensive time for us.

Maybe these researchers have seen too many Star Wars movies where the "midichlorians" (or however that's spelled) control everything through "The Force". When that concept first came out in Star Wars, I thought Lucas had totally lost it - it was brain dead.

OTOH, I've thought about Drexler's notion of embedding nanotech computers and robots into every cell of the human body. What would happen if you had trillions of human cells loaded up wi

A lot of them do. For example, Enterobius vermicularis will have you scratching your butt all day and all night. I supect that this behaviour will render you definitely UNSEXY to most people, as well as rather smelly and angry:)

That might be true, or the effect is the same (increases factor X in brain) but men and women react different to it because men already have a higher level of factor X in their brain. Like a little alcohol may make you more talkative/uninhibited/nice, but a lot makes you stupid or keel over.Btw: was the hetero remark to weed out the homophobes? you can never have enough enemies:)